I use it more for effect than with fluid lines; unless we're talking about the lower range from around F#3 to A3.
Depends upon the style of music and the audience you're playing for. Certainly a bunch of Berklee grads are going to tune out, but that's not your average audience. Anyhow, what I meant by "effect" would be this, beginning at the 1:47 mark:I’ve never really been a fan of someone just hitting that one note up high for an effect.
I consider Potter to be a technician up top, but I prefer Lenny overall. As for straining, that's showmanship, and I'd never begrudge that.Almost all of the modern 'straight ahead' players like Joel Frahm, Chris Potter, Melissa Aldana, Patrick Bartley, Mark Turner, Godwin Louis, and many others I can't think of now off the top of my head, use altissimo as a 'natural' part of the horn. There's much less of the 'OMG, I'm STRAINING up here' than there used to be.